Rain Detector

Description

This circuit uses a sensor made of a small piece of etched PC board and a simple SCR circuit to detect rain and sound a buzzer. The SCR could also be used to activate a relay, turn on a lamp, or send a signal to a security system.

Circuit diagram

Parts

R1 1K 1/4 W Resistor

R2 680 Ohm 1/4 W Resistor

D1 1N4001 Silicon Diode

BZ1 12V Buzzer

S1 SPST Switch

SCR1 C106B1 SCR 106CY

SENSOR See Notes

MISC Board, Wire, Case, PC Board (For Sensor)

Notes

The sensor is a small piece of PC board etched to the pattern showen in the schematic. The traces should be very close to each other, but never touching. A large spiral pattern would also work.